US1305015A - Electric system - Google Patents

Description

F. H. SHEPARD.

ELECTRIC SYSTEM.

APPLICATION FILED )ULY24.I914. RENEWED OCT-30.1918.

1,305,015. Patented May27,1919.

l E \ql i In 5 WlTgESSES:

ATTORN EY UNITED STATES PATENT OFFICE.

FRANCIS H. SHEPARD, OF NEW ROCHELLE, NEW YORK, ASSIGNOR TO WESTINGHOUSE ELECTRIC AND MANUFACTUBIN G COMPANY, A CORPORATION OF PENNSYLVANIA.

' ELECTRIC SYSTEM.

Specification ofLetteu Patent.

Patented May 2'7, 1919.

Application filed July 24, 1914, Serial No. 852,800. name October a0, 191s. Serial No. 260,380.

- To all whom'z't may concern:

1 Be it known that I, FnANors H. SHEPARD, a Citizen of the United States, and a resident of New Rochelle, in the county of Westches- 5 ter and State of New York, have invented a new and useful Improvement in Electric Systems, of which the following is a specification.

My invention relates to electric control systerns, and it has special reference to means for signaling to operators of electric railway trains and the like in order that the electrical conditions of the system may be variably controlled.

16 One object of my invention is to provide a simple, inexpensive and reliable means for apprlsing o erators of the several locomotives of an e ectric railway system, for exarnple, of the electrical load conditions of the 20 entire system in order that any operator may manipulate the apparatus under his control to vary the load conditions.

Another object of my invention is to aid, by means of a system of the above indicated 26 character, in preventing a predetermined power consumption in a transmission circuit from being exceeded while delivering a temporary abnormally heavy current to a receiving circuit, such as an electric railway 80 system, I v It is sometimes desirable, or even necessary, particularly in a case where a railway system purchases its power from an outside power company, thata predetermined maximum consumption of power shall never be exceeded, even under unusually severe operating conditions. It is especially toward means for preventing such an objectionable occurrence that my invention is directed; for, although, with an ideal distribution of trains, the power consumption may be kept within the specified limit, it is evident that such an ideal condition cannot possibly be maintained for any considerable length of time. p

In certain railway ele ctrific'ations, let it be assumed that the general layout is as follows:

At various sub-stations along the railway line, three-phase 6O cycle power is supplied by an outside company and is transformed,

by means of suitable frequency-changing ment of power circuits and locomotives may be employed.

The above-mentioned split-phase locomotives may operate on any frequency, within a given range, provided the voltage varies in IOPOltlOll'tO the frequency. For example, if the frequency dropped from the assumed normal value of 25 cycles to 20. or 15 cycles, and if the voltage decreased in the same proportion, the locomotives would 0 erate under practically the same tractive e ort as before and with the same current supplied to the motors, but the input to the locomotive would be reduced practically in proportion to the frequenc and voltage. Consequently, in the event 0 an overload on the railway system, if the frequency delivered by the sub-station is lowered, the railway load may be reduced also. In this way, the power consumption from a transmission circuit may be kept within a specified maximum but the train operation is sacrificed. In other words, whereas the specified power consumption from the transmission circuit is not exceeded, the overload current demanded by the trains in order to maintain desirable operating conditions is not supplied and the railway service suffers in consequence.

However, if the output of the frequency changer could be reduced in smaller propor tion than the decrease in frequency and voltage or could be maintained substantially constant during such decreases, then the demanded overload current could be supplied to the railway system without exceeding the specified power consumption from the transmission line and with good train operation. For instance, if the output of the frequency changer could be held substantially constant while the frequency and voltage were decreased 30%, then the current delivered to the locomotives could be increased approximately i07 and their tractive effort increased in' proportion. Thus, with such a system, by varying the frequency, but not regulation itself does not depend upon the I use of such motors and other systems employing such locomotives in part or not at all, may also secure a certain degree of benefit from the system. 7

With the above ends in view, I have aided in devising various systems for accomplishing the desired result. One such system comprises a direct-current motor that is mounted on the shaft of the frequency-changing set and a rotary converter connected between the secondary Winding of the driving induction motor of the set and'the direct-current motor. By varying the field strength of the direct-current motor, its armature voltage, as well as both the direct-current voltage and the dependent alternating-current voltage ,of the rotary converter, maybe varied, and thus the electro-motive force of the secondary winding of the induction motor may be changed. Moreover, if desired, automatic apparatus may 'be employed in combination with the above-mentioned system, whereby, when the input to the power station reaches a predetermined maximum value, the field of the direct-current motor is regulated to decrease the induction'motor speed and thus suitably reduce the frequency delivered by the generator, while keeping its output very nearly constant.

The above described system is fully set forth in a co-pending application filed by Benjamin G. Lamme and myself, December 26, 1913, Serial 808,716 and assigned to the Westinghouse Electric & M-fg. Company.

The system comprises a part of my present.

invention only in so far as it performs certain functions in the carrying out of my signaling system. I p

I According to my present invention, I pro 'de in connection with a control system of t above-described character a signaling system, whereby the train operators are apprised at all times of the relative load conditions of the system, and, in particular, receive signals denoting overload conditions immediately upon the occurrence thereof. In brief, the system comprises the use of sup ply-circuit frequency-indicating means, such as meters,. in the various trains, preferably disposed in front of theoperator where the indications may be readily' 'observed. By means of my system, the operator may, upon the occurrence of overload conditions, ma-

nipulate his apparatus to temporarily reduce or entirely interrupt the amount of power drawnfrom the supply circuit, in addition to the above mentioned regulating effect in the stations, thus aiding materially in the desired object of preventing the exceeding of a predetermined power consumption from the transmission line,

As a specific example, consider a single track electric railway provided with a plurality of relatively distantturnouts, and serving both high-speed passenger and heavy freight trains. It is highly important that the passenger trains keep on time and be not detained by low-Voltage and frequency conditions in the supply circuit that are caused by an excessive draft of power in the railway system as a whole. On the other hand, the freight locomotives, which consume a large amount of power, as compared with the passenger trains, are not ordinarily held to such strict schedule requirements, and often, the operators of freight locomotives, by reason of the varying haulage 'conditions,have

a considerably greater amount of time availto reach the next turnout before the passenger train to be passed is due at that point. Consequently, when the operator of a freight locomotive is apprised, by the use of my signaling system, of the existence of an abnormal electrical load in the railway system immediately upon the occurrence thereof, he can thereupon run his locomotive at half speed or shut off power entirely, according to the amount of extra time available and on other obvious conditions. Thus, without waiting for semaphore indications or telephone messages or the like, the operator can immediately lower the electrical load on the system, an can proceed the instant that the 1 power conditions have reassumed their norentire railway system is afforded; So far as I am aware, my system is the first ever'proposed wherein the load conditions of the entire system, particularly in the case of abnormal load, are automatically and simultaneously indicated at a number of points in such a system.

The single figure in the accompanying dra'w1ng,1s a diagrammatic View of a system of control embodying my invention.

Referring to the drawing, the electrified railway system here shown comprises a threephase transmission line 1 of relatively high frequency which, as hereinbefore stated, for

the purposes of this application, may be considered as the property of an outside power company; a plurality of spaced substations 2 supplied with power from the bus 1 and 'severall provided with a suitable frequency-changing set 3 and accessory apparatus, as hereinbefore specified; a singlephase railway circuit 4, fed from the sets 3; a suitable number of trains supplied from the circuit 4 and severally comprlsing a locomotive 5 and one or more coaches 6;.and a plurality of frequency-indicating means, such as meters 7, that are severally suitably located in the locomotives.

In the single figure of the drawing the frequency-changing sets 3 are shown as severally comprising a three-phase lnductlon motor 8 that is suitably connected to the transmission line 1, either directly or through transformers (not shown) and an alternating current single-phase generator 9 for supplying the railway circult 4 with voltage of a suitably low frequency. A small direct-current motor 10, preferably having a shunt field magnet winding 11, is mounted on the shaft of the set 3 and is adapted for variable excitations, the field winding 11 having a variable resistor 12 in circuit therewith.

A rotary converter 13, of any I suitable type, has itsalternating-current end connected to the secondary winding of the 1nduction motor 8 and its direct-current end connected across the circuit of the motor 10.

An electromagnetic device 14 is preferably employed, in connection with the field resistor 12, to automatically regulate the field current, as hereinafter described. The

device shown is intended to be merely illus trative, it being understood that other automatic apparatus for accomplishing the purpose may be employed, if desired. The device 14 may comprise a solenoid 15 that is connected in. a main line conductor, and the core 16 of which is operatively connected, at one end, to the movable member of the resistor 12; and a dash 0t 17, or other suitable member for retar ing the removal of resistance from the field circuit, may or ma not be secured to the other end.

motor embodying an armature 50 and a field winding'49 is connected across the railway circuit 4 by means of thetransformer 41 having aprimary winding 42 and a secondary winding 43. A plurality of switches 44, 45, 46 -"and 47 and a preventative coil 48 of usual construction are pro vided for connecting the motor across vari ous portions of the secondary winding 43, in order to effect acceleration of the motor.

Since the acceleration of the motor is self-- evident from the drawing, a further description thereof is deemed unnecessary.-

-tro-magnets 18 and 19, one of which is in series with a resistor 20 and the other with a reactor 21, the two circuits referred to being connected in parallel across the receiving circuit 4; a pair of suitable cores 22 and 23 respectively associated with the two electromagnets 18 and 19; and a disk 24 adapted to be rotated in either direction, according to the relative strengths of the two electro-magnets. The dial 25 of the meter may be calibrated in any suitable manner, for example, with a pair of limiting marks between which the operator is to keep the indicating pointer 26, in percentages of the total permissible load of the system.

The operation of the meter may be briefly described as follows: when the forces exerted by the cores of the. two electromagnets 18 and 19 upon the disk 24 are balanced, the disk remains at rest, the pointer 26 assuming a position correspondin to a certain frequency of the circuit. en the frequency undergoes a change, the relative strength of the two electro-magnets is varied by reason of the different actions upon their respective circuits of the resistor 20 and the reactor 21, and, consequently, the disk 24 an incipient overload, that is, as soon as a predetermined maximum power input and resultant current per phase is reached, the solenoid 15 lowers the core 16 and, consequently, the movable member of the resistor 12 is operated against the action of the dashpot 17, if one is employed, to exclude resistance from the field circuit of the directcurrent motor 10, the said movable member tending to take the position shown in dotted lines. The field flux is thus strengthened and the armature voltage increased, whereby the dlrect-current voltage and dependent alternating-current voltage of the rotary converter are increased proportionately, and

the voltage of the secondary winding of the induction motor 8 is raised. As a result, the speed of the induction motor and the associated alternatingcurrent generator is reduced, thus also reducing thefrequency and voltage produced b the generator. The final result is that t epower output of the frequency-changing set 3 is maintained sub stantially constant, but a much increased current is delivered by the generator, as already explained.

Moreover, each operator is immediately apprised, by, his frequency meter 7, of the decrease in the receiving circuit frequency and the accompanying increase in load conditionsof the system and may manipulate the apparatus of his locomotive to aid in reducing the power consumption until the temporary peak load has passed, as hereinbefore described. In this way, the railway system may be temporarily satisfactorily supplied with an abnormal current without exceeding the specified maximum power consumption in the transmission line.

While I have disclosed my signaling system in connection with a control system of a particular type, it will be understood that my system can be readily applied to various other kinds of control systems, and I desire that'only such limitations shall be imposed as are indicated in the appended claims.

I claim as my invention:

1. In an electrical system, the combination with a supply circuit, of a plurality of electrical devices adapted to receive energy therefrom at different points, and means. disposed at certain of said points and electrically'associated with the supply circuit for continuously indicating ,the electrical load of the entire supply circuit. i

2. In an electrical system, the combination with a supply circuit, of a plurality of differently located electrical devices severally adapted to receive energy therefrom, at the will of operators, and a plurality of elec-- tors for indicating the electricalconditions of the supply circuit.

4. In an electrical system, the combination with a supply-circuit and a dynamoelectric machine for supplying energy thereto, of a plurality of differently located electrical devices, means to supply said devices with energy from said supply circuit at the will of operators, and means for severally indicating to the operators the existence of predetermined load conditions on the machine, whereby any operator may. manipulate his device to vary said load conditions.

5. In an electrical system, the combination with a supply circuit and an alternatmg current dynamo-electric machine for supplying energy thereto, of a plurality of vehicles, means for supplying said vehicles with varylng amounts of ener y from said circuit, at the will of operators, meansdependent upon predetermined load conditions for oppositely varying the frequency of the machlne, and means for severally indicating the supply circuit frequency \to the operators, whereby any operator may be notified to operate his vehicle to vary said load conditions.

7. In anelectrical system, the combination with asupply circuit, and a plurality of vehicles adapted to receive energy therefrom, of means positioned in proximity to certam of said vehicles for indicating the existence of a predetermined electrical load in the entire supply circuit and means for varying said load as desired by the manipulation of certain of said vehicles.

8. In an electrical system, the combination with a supply circuit and an alternating current dynamo-electric machine for supplying energy thereto, of a plurality of translating devices severally adapted to receive varying amounts ofenergy therefrom, means dependent upon load conditions for varyingthe frequency of the machine, means associated with said devices for indicating the electrical load'conditions of the entire supply circuit, and means for regulating said devices to independently vary said load conditions.

9.. In an electrical system, the combination with a transmission circuit and a receiving circuit, and a plurality of mechanically associated dynamo-electric machines respectively operated from said transmis- 10 sitioned near said devices for indicating the frequency conditions of the receiving. circuit, and means for severally regulating any of said devices to independently vary said load conditions.

In testimony whereof, I have hereunto 15 subscribed my name this 9th day of July 1914.

4 FRANCIS H. SHEPARD.

Witnesses:

WM. H. CAPEL, G. Wnsnnr Pomor.

Images